The invention is used, for example, in pneumatic drilling machines which are used in aircraft construction.
A machine of the above-mentioned type is known, for example, from EP-A-1 618 978. The drive mechanism of such a machine is referred to as “having positive feed” in English (or “à avance mécanique” in French).
A single motor thus ensures, via the drive mechanism, that the spindle is rotated about the axis thereof and, at the same time, that it is advanced or returned by translation along the axis thereof.
Since the translation and rotation drives of the spindle are connected mechanically, the advance of the spindle per revolution is constant. In this manner, the variations in speed of the motor do not have any effect on the advance per revolution. The thickness of the chips formed therefore remains constant and promotes the surface quality and the precision of the holes which are drilled by such a machine.
Drilling some materials which are known to be difficult, in particular composite materials, sometimes necessitates high tool rotational speeds.
However, such a machine cannot be used at high speed, that is to say, for example, at 15,000 rpm, without encountering premature wear of the drive mechanism, or even breakage.